Everything a dual-clutch automatic gearbox, DSG, can do for you

More and more drivers are leaving manual gearboxes behind in favour of automatics, but do you know everything a dual-clutch automatic gearbox or DSG can do for you? This technology was born forty years ago and soon went on to revolutionise the driving capability of cars.

The dual-clutch transmission, DSG, has now become a common feature on most cars, to the point of exclusivity on some. It was devised by a small team of engineers at Porsche who, as they admitted themselves, were probably punching above their weight at the time.

The Porsche Doppelkupplungsgetriebe (PDK transmission) was almost too far ahead of its time in the early 1980s. Computing power was a fraction of what it is today, but the engineers managed to make it work well enough to gain major advantages in Group C racing with the Porsche 962 and in rallying with the Audi Quattro S1. So now, when the technology has not only been refined but has evolved into something far better than was ever originally imagined.

Everything you need to know about DSG gearboxes

The idea behind the DSG is that, in theory, it should be possible to change ratios without any interruption in torque in just a few milliseconds. By splitting the forward gears of the gearbox between two separate clutches, each forward gear can be pre-selected and the ratio changed by simultaneously opening and closing the clutches, removing one ratio from the equation and bringing the other into play. The shift is not made by physically selecting each gear as needed, but by opening and closing the clutches.

In those early days, the lack of processing speed meant the shifting was difficult. The inability to perfectly synchronise the clutches resulted in violent forward jolts, placing great stress on the driveline at the same time. Refinement and robustness were not there to meet the needs of everyday road cars.

Twenty years later, high-speed processing and the development of motorcycle-style wet clutch technology (oil-bathed clutches rather than dry air-cooled ones) finally made the DSG a perfect production reality. During the DSG’s transition period from competition, automated manuals with a single clutch arrived, such as the Selespeed from Alfa Romeo and the SMG from BMW. Both were criticised for being slow compared with a manual, even though the figures suggested otherwise. One engineer attributed this discord to perception, because the driver had nothing to do while the shift was taking place. That may well have been the case, and it is probably also the reason why the unquestionably faster DSG gearboxes remain unpopular with some drivers.